Earlier quoted context omitted.
The plan I have currently has a $6k deductible for my family, for in-network care - $10k outside of network. This would not bankrupt us currently, no, but it would have as recently as a few months ago, and almost all other times in my life.
I thought that the vast majority of healthcare providers are amenable to payment plans and other forms of assistance.
However, your room for negotiation is much smaller when you're paying a huge insurance deductible than if you're completely uninsured. Hospitals charge outrageous prices for the uninsured, partly so they have room to make a profit when insurance companies negotiate down, partly to make up for the fact that a lot of uninsured people will never pay, and partly because some people will pay it so they might as well try.
If you're insured with a high deductible, the insurance company has already negotiated prices down by an order of magnitude. Any further negotiation with your deductible starts to really hurt their bottom line, and might run into problems with their arrangement with the insurance company too.
I have to imagine that a payment plan could be arranged without too much difficulty, but actually reducing the total amount could be challenging.